Semi-starvation in anorexia nervosa and other conditions may be associated with sudden death and high output failure during rehabilitation. Abnormalities of heart rate, blood pressure and plasma catecholamines have been noted in anorexia nervosa patients. This study will evaluate cardiac and autonomic nervous system changes during nutritional rehabilitation of these individuals using non-invasive cardiac diagnostic techniques including echocardiography, exercise testing, 24-hour ambulatory ECG monitoring. Plasma norepinephrine at rest and exercise will be measured in parallel with these studies.